ar083.yang01 Posted: 25-Apr-95 Updated: 16-Sep-95, 27-Jan-97 Evets specified: AR 7321, AR 7773, etc.
by Yang Liu, Yihua Yan (Beijing Astronomical Observatory, Chinese Academy of Sciences, Beijing 100080. TEL:86-10-2612194,FAX:86-10-2561085 EMAIL:YYH@bao01.bao.ac.cn) Maki Akioka (Solar Division, Hiraiso Solar Terrestrial Research Center, Communications Research Laboratory) and other collaborators are welcome.
MOTIVATION:
It is believed that solar magnetic fields dominate solar atmospheric activities, and some recent studies have indicated that the magnetic topology of an active region is a determining parameter in the flare productivity. However, such a 3-d solar magnetic field structure above the active region can only be obtained from some extrapolating procedure because the reliable observing data are confined to the photosphere or incompletely at other levels. We have carried out the analysis of extrapolated 3-d magnetic structures above NOAA 6659 in June 1991 and found the complicated magnetic topological structures at chromospheric level and low corona, which tend to become rather simplized loop strucutures or open field at higher levels. However as there were lack of other observations at higher levels for NOAA 6659, we hope to investigate the relationship between magnetic strucutres and physical process above active regions for other events. DATA AND METHOD:
The Hairou vector magnetograms are used as boundary conditions to extrapolating the 3-d magnetic structures above active regions. Then we wish to identify the correspondence between the magnetic topology and the simultaneously observed SXT, HXT, H-alpha, H-beta, chrosmospheric magnetogram, or radioheliograph data when these are available.
EVENTS:
We have already found the simultaneous observation by different instruments for: NOAA 7321 on 27 October, 1992 (at UT0056, 0224, 0301, 0332, 0419 by Huairou) we wish to get the Yohkoh SXT and HXT data at corresponding time. NOAA 7773 on 5-6 September, 1994 (at UT0230,0300,0330,0400,0430,0500 by Huairou) we also wish to get the Yohkoh data at those instants.
The effort to find more data set will be continued.
Update 27-Jan-97
Abstract (Solar Physics, submitted)
An analysis of photospheric vector magnetograms, H_alpha images and soft x-ray images in a superactive region NOAA7321
Yang Liu, Maki Akioka, Yihua Yan and Guoxiang Ai
Based on the photospheric vector magnetograms taken at Huairou Solar Observing Station, H_alpha images taken at Hiraiso Solar Terrestrial Research Center of Communication Research Laboratory, soft X-ray images taken by YOHKOH and an extrapolation method, the configuration of magnetic field and some active phonomena around 04:00 UT on 1992 october 27 were analysed in this paper. A divergence of the transverse magnetic field, located at a new formed spot, was found. At least four highly sheared magnetic field systems separatively spreaded from this divergence to other four sites around this divergence. Vertical current concentrations are upward in this region and downward in the other four sites, and the corresponding H_alpha bright patches and soft x-ray bright loops coincide with these structures, confirming the existance of these four systems. The extrapolated magnetic force lines reconstructed by the Boundary Element Method, force-free field assumption and boundary condition of observed photospheric vector magnetic field, coincide in space with the H_alpha bright patches and soft x-ray bright loops, showing that this extrapolation method is very effective and suggesting that the H_alpha bright patches and soft x-ray loops in this case represent the magnetic field structures in the upper atmosphere of the Sun.
Update 16-Sep-95
We have already installed the YOHKOH software in our SUN SPACX 10, based on the IDL environment. It works well. The simulation, based on the Boundary Element Method(BEM), has also been done by means of our observed magnetic fields taken in HUAIROU SOLAR OBSERVING STATION. We will discuss these results sooner. We will report other process if we deduce in future.